For producing tablets containing water-soluble vitamins such as L-ascorbic acid as an active component, a large amount of a binder is required, which limits a L-ascorbic acid content. Many activities have been attempted to produce tablets having a high L-ascorbic acid content and tablets having high mechanical strength (hardness).
For example, in U.S. Pat. No. 3,453,368, 85 to 95% by weight of L-ascorbic acid is mixed with 5 to 15% by weight of modified starch and the mixture is subjected to wet kneading. Then, the resultant mixture is granulated and dried to obtain granules containing L-ascorbic acid, mixed with a lubricant and compressed to obtain tablets containing L-ascorbic acid.
However, according to this method, it is difficult to obtain homogenous granules and fluidity of the granules is not satisfactory. Moreover, tablets prepared using the granules have insufficient mechanical strength (hardness).
In general, tablets need certain mechanical strength (hardness) to prevent breakage and wear during production and marketing steps and use. Then, activities have been attempted to investigate production processes, various excipients, binders, disintegrators and lubricants.
JP-B 58-403 discloses a process for production of L-ascorbic acid granules having excellent compressibility which comprises fluidizing L-ascorbic acid powder which can pass through a 200 mesh sieve in a fluidized bed granulator, while spray-coating the granules with a solution containing about 1 to about 10% by weight of a binder such as a water-soluble, organic solvent-soluble cellulose material to obtain granules containing about 2 to about 4% by weight of the binder. This patent also discloses a process for producing a pharmaceutical preparation which comprises mixing a lubricant with the above-obtained L-ascorbic acid granules and compressing the resultant mixture into a tablet.
JP-B 61-21526 discloses granules for tablets having a specific distribution of particle size comprising about 98:5 to 99.5% by weight (dry matter) of sodium L-ascorbate and a binder such as a water-soluble, organic solvent-soluble as cellulose material, and a tablet using the granules.
JP-B 5-66928 discloses granules for tablets having a specific distribution of particle size, wherein soluble polyvinyl pyrrolidone and ascorbic acid are used, and there is disclosed that a tablet having a high disintegration rate is obtained.